The present invention relates to a device for driving and stopping a roll blind.
A roll blind consists of a blind cloth and a winding roll for winding up or unwinding said blind cloth. A device for driving and stopping the roll blind, heretofore used, comprises a coil spring for constantly applying a force to said winding roll in the cloth winding up direction and a ratchet mechanism for stopping said winding roll against the force applied by said coil spring to stop the blind cloth at a desired position, in which at the time of lowering the blind cloth the ratchet mechanism is actuated under centrifugal force to stop the blind cloth at the desired position and at the time of raising said blind cloth the ratchet mechanism is released by slightly moving the blind cloth downward, whereby the blind cloth is allowed to be wound up onto the winding roll under the action of said coil spring.
The conventional device for driving and stopping the roll blind, as described above, requires troublesome operation to correctly stop the blind cloth at a desired position, and consequently it is difficult to correctly stop the blind cloth at a desired height. Furthermore, it is difficult to wind the blind cloth smoothly onto the winding roll.